Method of texturing triacetate yarn



April 11, 1967 R. J. LOFTIN ET AL 3,313,011

METHOD OF TEXTURING TRIACETATE YARN 7 Filed Oct. 14, 1963 United States Patet 3,3l3,0ll Patented Apr. 11, 1967 Flee 3,313 011 METHOD 6F TEXTURIl lG TRIACETATE YARN Robert J. Loftin and Earl H. Hartgrove, Charlotte, NC, assignors to Ceianese Corporation, a corporation of Delaware Filed Oct. 14, 1963, Ser. No. 316,074 11 Claims. (Cl. 28-76) This invention relates to an improved textured or voluminous yarn. More particular, the invention relates to a method for the production of an improved textured yarn of a cellulose triester such as cellulose triacetate.

The texturing or voluminizing of yarns has been found useful for the purpose of increasin the bulk, and improving the hand, drape, covering power and loft of fabrics manufactured from such yarns. Thus, using such textured yarns, a fabric may be made having greater cover and bulk for a given weight of yarn than when untextured yarn is used, or less weight of yarn may be used to obtain a certain degree of cover and bulk.

In addition to the above advantages, fabrics made from textured yarn-s generally yield greater comfort because of improved moisture absorption, have excellent esthetic appeal and dimensional stability as compared with fabrics made from untextured yarn, and have better resistance to fuzzing and pilling as compared with fabrics made from spun yarn.

Various difficulties have been encountred in utilizing textured yarns of a cellulose triester such as cellulose triacetate prepared by methods used heretofore. Thus it has been found in some cases that too large a portion of the bulk imparted to the yarn is lost during subsequent proc essing of the yarn and fabric. Moreover, the physical properties of the yarn such as the tenacity has often been found to suffer to too large an extent as a result of the texturing. In some cases, also, the bulk imparted to the yarn is not as uniform as would be desired.

It is an object of this invention to provide an improved textured yarn of a cellulose triester such as cellulose triacetate.

It is a further object of this invention to provide a method for the texturing of a continuous multifilament yarn of cellulose triacetate yielding a product having improved properties and avoiding or minimizing the foregoing diificulties.

Other objects will be apparent from the following detailed description and claims.

In accordance with one aspect of the invention, a yarn of a cellulose triester such as cellulose triacetate, is twisted, e.g., by a false twisting device such that it contains about 18 to 75 turns per inch; desirably, e.g., for 200 denier yarn, the twist is in the range of about 30 to 46, preferably about 32 to 36 turns per inch and most suitably about 34 turns per inch. While the yarn is in such twisted condition, it is fed to a temperature zone where it is heated to a temperature of about 170 to 200 C.; desirably, e.g., for 200 denier yarn, the temperature is in the range of about 180 to 200 C. preferably about 185 to 195 C. and most suitably about 192 C. The yarn is heated for a period of about 4.5 to 0.030 seconds; desirably, e.g., for 200 denier yarn, the period of heating is in the range of about 3.0 to 0.030 seconds preferably about 1.25 to 0.64 seconds, and most suitably about 1.02 seconds. The temperature zone is located on the yarn path before the point at which twist is inserted into the yarn, e.g., by a twisting device such as a false twist spindle. The twist is translated back along the length of the yarn in the direction of the incoming yarn until a point at which the twist is held in the yarn, e.g., by feed rollers or a snubbing device. After leaving the temperature zone and twisting device, the yarn is advanced, e.g., by feed rollers, at rate of about 99 to 109%, preferably about 101 to 104%, and most suitably, e.g., for 200 denier yarn, at about 101% of the rate at which the yarn is fed to the temperature zone, the latter value being alternately identified as a 1% underfeed to the advancing means, e.g., feed rollers, beyond the temperature zone and twisting device. The untwisted and now cool yarn is subsequently allowed to relax in an amount of about 0 to 30%, preferably about 3 to 20%; desirably, e.g., for 200 denier yarn, the relaxation is in the range of about 3 to 16% and most suitably about 4% before it is taken up on a yarn pack-age.

The aforementioned steps may be accomplished by feeding the yarn to the temperature zone and twisting device at a certain rate by yarn advancing means, e.g., feed rollers, which pull the yarn from a yarn source, e.g., one or more yarn packages. After the yarn leaves the temperature zone, it is advanced by second yarn advancing means, e.g., feed rollers, at a rate within the aforementioned ranges, e.g., of about 99 to 109%, of the rate at which the yarn is fed to the temperature zone and twisting device.

If stretch yarn with high bulk and elasticity is desired which is suitable for such ultimate uses as stretch hose and ski wear, the yarn is fed directly from the second yarn advancing means to yarn take-up means, e.g., one or more yarn packages, which take up the yarn at a rate of about to 70%, preferably about 97 to 80% of the rate at which the yarn is advanced by the second yarn advancing means; desirably, e.g., for 200 denier yarn, the take-up speed is in the range of about 97 to 84% and most suitably about 96% of said rate. These rates correspond to the rates at which the yarn is allowed to relax as given above and the 96% rate corresponds to a 4% relaxation rate accomplished by a 4% overfeed to the yarn take-up means.

If a textured yarn is desired with particularly high bulk characteristics and low elasticity which may be made into fabric of exceptionally good stability for use, for example, in blouses, double-knit fabrics, etc., the yarn is not passed from the second yarn advancing means directly to the yarn take-up means, but rather is passed through a second temperature zone where it is heated to a temperature of about to 200 (3., preferably about to 192 C. and most suitably, e.g., for 200 denier yarn, about C., for a period of about 4.5 to 0.30 seconds; desirably, e.g., for 200 denier yarn, the period of heating is 1.25 to 0.64 seconds, and most suitably about 1.04 seconds. After passing through the second temperature zone, the yarn is advanced by third yarn advancing means, e.g., rollers, which advance the yarn at a rate of about 100 to 40%, preferably about 96 to 70% and most suitably, e.g., for 200 denier yarn, at about 86% of the rate at which the yarn is advanced by the second yarn advancing means. From the third yarn advancing means, the yarn passes to the take-up means where it is taken up at a rate within the range of about 97.6% to 107.9% of the rate at which the yarn is advanced by said third yarn advancing means.

It has been found that the ranges set out above for the temperature at which the yarn is heated while twisted, and the rate at which the yarn is advanced by the yarn advancing means just beyond the first temperature zone and twisting device are critical in obtaining a textured yarn of high or maximum bulk as indicated by crimp contraction. Moreover, said range at Which the yarn is advanced by the yarn advancing means beyond the first temperature zone and twisting device, and the range set out above for the twist in turns per inch in the yarn which is heated, are critical in obtaining a textured yarn of high or maximum tensile strength.

The method may be further illustrated with reference to the drawing wherein continuous multifilament yarn 10 is taken from yarn supply package 11, passed through pigtail guide 13, passed around pigtail guide and broken end device 15 and advanced by rollers 16 (first yarn advancing means). The yarn is then passed through first temperature zone 17 and is twisted by false twist spindle 19 from where the twist is translated back to rollers 16. From false twist spindle 19, the yarn is advanced by rollers 20 (second yarn advancing means) from which the yarn may take one of two paths. If a yarn having a high degree of elasticity is desired, the yarn takes path A, and is passed directly from rollers 20 to pi-gtail guide 21 and guide bars 22 and 23 and is taken up by yarn take-up package 24.

If a yarn having particularly high bulk and low elasticity is desired, the yarn follows path B, and is passed through second temperature zone 26 to rollers 27 (third yarn advancing means) and thence to guide 21, guide bars 22 and 23 and yarn package 24.

Whether the yarn 'foliows path A or path B, the actual twist accomplished by false twist spindle 19 is substantially removed by the time'the yarn reaches rollers 20.

The process may be used to treat untextured yarn having a total denier, for example, in the range of about 55 to 1000, an initial twist in the range of about to 7 turns per inch, and compose-d of about 3 to 300 filaments.

The false twisting device referred to above is preferably a high speed false spindle of any of various types known in the art, e.g., that described in Patent No. 2,990,- 674 of Stoll et al. The spindle preferably rotates at a speed, for example, in the range of about 20,000 to 500,000 rpm, and the twist accomplished by the spindle should be in a direction opposite that of the twist of the supply yarn. Any residual twist present in the initial yarn should be taken into account when operating the twisting device in accordance with this invention so that the yarn contains the desired amount of twist in the temperature zone.

The process may be used to texture yarn at a rate based on the supply yarn in the range of, for example, about to 400, preferably 30 to 100 yards/minute.

To substantially maintain the bulk resulting from the above-described process, the tension on the textured yarn during subsequent processing is maintained as low and as uniform as possible. For example, it may be advanta geous to maintain the tension on the yarn during coning within the range of about 0 to 8 grams, when the feed yarn has a total denier in the range of about 55 to 1,000. Moreover, when it is desired to ply yarn having a total denier of about 110 to 3,000 using a spindle speed of about 4,400 to 6,200 rpm. subsequent to texturing, the tension above the feed rollers may be maintained, for example, in the range of about 0 to 3 grams for two ply or three ply yarn. Between the feed rollers and the guide above the bobbin normally utilized in plying, the tension may be maintained, for example, in the range of about 3 to 30 grams for two ply yarn and about 5 to grams for three ply yarn.

When plying yarn, it is preferable that the finished plied yarn be balanced, i.e., substantially torque free. This may be accomplished by plying yarns which have been textured in opposite twist directions.

The process of this invention using a single temperature zone may be used to produce textured yarns having a tenacity in the range of about 0.99 to 1.3, preferably about 1.1 to 1.3 grams/denier, an elongation in the range of about 20 to 35, preferably about 22 to 30%, an initial modulus in the range of about 9 to 28, preferably about 20 to 25 grams/denier/unit elongation, and a high degree of bulk, as indicated by a crimp contraction of about 8 to 30% preferably about 15 to 30%, and an elastic recovery of about 30 to 50, preferably about 42 to 50%. Moreover, using two temperature zones, the method may be used to produce relatively textured yarns of low clasticity having a tenacity of about 0.99 to 1.3, preferably about 1.1 to 1.3 grams/denier, an elongation of about 20 to 35, preferably about 24 to 28%, an initial modulus of about 9 to 28, preferably about 20 to 25, a crimp contraction of about 8 to 20%, preferably about 8 to 15% and an elastic recovery of about 30 to 50%, preferably about 42 to 50%.

The textured yarn product generally has a tenacity in the range of about to of the tenacity of the original untextured yarn, and a tensile factor (product of the tenacity in grams/denier and the square root of the percent elongation) of about 80 to 105% of the tensile factor of the untextured yarn. These percentages are higher than those obtained when the yarn is textured using various process conditions outside the scope of the invention.

The textured yarn of this invention is particularly suitable for use in knitted fabrics which may be produced using any of a variety of single and double needle circular knitting machines. Yarn tension during knitting is preferably maintained at about 3 to 5 grams and as uniform as possible. The yarn is prefarably fed to the knitting needles by positive feed rolls to assist in maintaining tensions as uniform as possible. Woven fabrics may also be made from the textured yarn of this invention.

In accordance with another aspect of the invention, the bulk of a knitted fabric produced from the textured yarn produced as described above is more fully developed and fabric-stitch relaxation is obtained by tumble drying the fabric before wet processing, i.e., scouring, dyeing and finishing, at a temperature of at least about 220 F., preferably about 220 to 225 for a period of about 20 to 30 minutes. This may be accomplished using a machine with a drum that alternately rotates clockwise and counterclockwise for about 15 to 20-seconds in each direction. Before removing the fabric from the tumbler, it is advisable to cool to about to F., preferably about 150 F. with continued tumbling prior to removal from the machine to prevent setting any creases and wrinkles. The fabric should be turned inside-out prior to tumbling.

To preserve the maximum bulk of the knitted fabric, it is desirable to autoclave set the fabric prior to wet processing. The autoclave setting may be accomplished, for example, by exposing the fabric to steam at a pressure of about 15 to 35 p.s.i.g., preferably about 30 p.s.i.g., corresponding to a temperature of about 250 to 280" F., preferably about 274 F., for a total period in the range of about 20 to 40 minutes. Desirably, relatively short periods of steaming, e.g., about 2 to 5 minutes are inter spersed with short periods of vacuum in the autoclave, e.g., a vacuum of about 20 to 30 inches of mercury for a period of about 3 to 8 minutes. The last period of steaming should be longer than those initially used, e.g., about 20 to 30 minutes.

The fabric of textured yarn to cellulose triacetate is preferably prepared for autoclave setting by slitting it so that it can be autoclaved in open width form. The fabric is suitably batched onto a perforated shell in the autoclave wit-h a cotton interliner fabric between each layer of knitted textured yarn fabric to prevent moire formation.

After autoclave setting, the knitted fabric may be scoured and dyed, for example, in a paddle wheel machine or in a winch. The dyeing is generally carried out using an aqueous solution of a disperse acetate dye, e.g., any of those listed in the Colour Index, second edition on pages 1659 to 1752. The dyebath may contain, for example, about 0.1 to 10% by weight of dye and the dyeing may be carried out, for example, at a temperature of about 95 F. to boiling, preferably about to F. The dyebath may contain in addition to the dye, a dye assistant or accelerant such as butyl benzoate, methyl salicylate, acetyl triet-hyl citrate, or butyl Cellosolve acetate which may be present in an amount of about 2 to 6 grams/liter of dyebath. A dispersing agent and a wetting agent may also be present. A liquor: fabricweight ratio in the range of about 20:1 to 3021 may be used. After dyeing, the fabric may be after-scoured to remove excess dye.

If desired, the fabric may be finished to modify its hand. For a soft hand, a cationic finish may be applied in an amount of about 0.25 to 0.5% based on the weight of the fabric, while for a stiffer and harsher hand, the fabric may be coated with a resin emulsion in an amount of about 0.5 to 1.0% based on the weight of the fabric. The fabric may then be dried, for example, on a reel or loop dryer after centrifuging to remove excess liquid.

The invention is further illustrated by the following example:

Example Referring to the drawing, a continuous multifilament yarn consisting of 52 filaments of cellulose triacetate having an acetyl value of about 61%, a total denier of about 200, and a light twist of about 0.25 turn of Z-twist per inch is fed by rollers 16 to the first temperature zone, i.e., heater 17 and false twist spindle 19 at a speed of 36 yards/minutes. False twist spindle 19 is operated at a speed of 4,000 r.p.m. which causes a twist in the S direction to be inserted in the yarn between spindle 19 and rollers 16 of 34 turns per inch. Yarn containing such twist is heated to a tempearture of 192 C. for a period of 1.02 seconds.

The yarn from false twist spindle 19 loses most of its twist and is advanced by rollers 20 at a speed of 36.4 yards/minute which is 101% that at which it is fed by rollers 16. This is equivalent to a 1% underfeed to rollers 20. The yarn from rollers 20 travels along path A through pigtail guide 21 and guide bars 22 and 23 to yarn take-up package 24 where it is taken up at a speed of 33 yards per minute which is 96% of the speed at which it is advanced by rollers 20. This corresponds to a 4% overfeed to take-up package 24.

The textured yarn produced by the foregoing process has a tensile strength of 225 grams corresponding to a tenacity of 1.13 grams/denier, an elongation of 24%, an initial modulus of 20.3 'grams/deni-er/unit elongation, and a bulk indicate-d by a crimp contraction of 9.8%.

The textured yarn is coned using a start-up at 6 grams tension and continuous tension relief to compensate for increasing yarn speed. The tension is relieved to 4 grams for 1 /2 to 2 pound package. A yarn lubricant is applied during coning.

A circular knit fabric is prepared from the textured yarn using a double needle circular knitting machine, maintaining yarn tension at 3 to 5 grams and as uniform as possible. The yarn is fed to the knitting needles by positive feed rolls to assist in maintaining uniform tensrons.

To develop the bulk, and relaxthe stitching of the fabric, it is turned inside out and tumbled in a hot air tumbler for about 30 minutes at 220-225 F. in a machine with a drum which alternately rotates clockwise and counter-clockwise for 15-20 seconds. The fabric is cooled to 150 F. with continued tumbling prior to removal from the machine.

The fabric is slit to open-width form and batched onto a perforated shell in an autoclave, with a cotton interliner fabric between each fabric layer of textured triacetate yarn. The following cycle is used to autoclave set the fabric: vacuum of 26 inches Hg for 5 minutes; 30 p.s.i.g. steam for 3 minutes; 26 inches vacuum for 5 minutes; 30 p.s.i.g. steam for 3 minutes; 26 inches vacuum for 5 minutes; 30 p.s.i.g. steam for 30 minutes; and 26 inches vacuum for 5 minutes.

The fabric is then removed from the autoclave and maintained open-width on the shell until cooled to below 120 F.

The fabric is put into open mesh bags which are placed in a paddle wheel dye machine. For scouring, the machine is filled wth water and run for 5 minutes after which 1 gram/liter of tetra sodium pyrophosphate and 1 gram/ liter of sodium N-methyl N-oleoyl taurate, as an anionic detergent, are added, and the bath is heated to 160 F.

6 and maintained at that temperature for 20 minutes. The material is then cooled and rinsed with hot water.

To dye the fabric light blue, the paddle wheel machine containing the fabric is filled with water to which is added 1 gram/liter pf. Dianol S, i.e., a sodium alkyl aryl sulfonate, as a wetting agent and low foaming detergent, and 0.75 gram/liter of Tamol SN, a neutral sodium salt of a condensed aryl organic acid, as dispersing agent. The machine is run for 5 minutes while maintaining the bath at 50 C. after which 1 gram/liter of butyl benzoate is added, and the machine is run for an additional 5 minutes. An amount of Latyl Brilliant Blue BG dye (C.I. Disperse Blue 60) is then added in an amount such that the dye concentration is 0.5% by weight, the machine is run for an additional 5 minutes and the bath is then brought up to a boil in 30-45 minutes. The bath is kept at the boil for at least one hour and sampled. When the desired shade is reached, the fabric is cooled with an outside spray to F., rinsed and cooled with hot water, and rinsed and cooled with cold water. The machine is then drained and the fabric is finished by treating it with an aqueous solution of 0.5 gram/liter of dimethyl distearyl quaternary ammounium chloride as softening agent, for 20 minutes at 45 C.

The fabric is then extracted bycentrifuging for one minute and dried at 200 C. by passing it through a reel drier at 15 yards/minute, using 8% lengthwise overfeedQ A loop drier may also be used.

Use of the above procedure results in the production of a substantially uniformly dyed, relatively elastic, knitted fabric of high bulk and excellent hand, cover and loft.

The described procedure is carried out except that the yarn from rollers 20 follows path B rather than path A. The yarn is heated in temperature zone 26 to 185 C. for 1.04 seconds and is advanced by rollers 27 at a rate 86% of that at which it is advanced by rollers 20. The yarn is then taken up by take-up package 24 at the same rate as that at which it is advancedby rollers 27.

The latter procedure results in a uniformly dyed fabric having a lower elasticity than that produced when the yarn follows path A.

As indicated above, the dyeing step may be conducted using a winch. When a standard elliptical reel is used, the reel speed is about 15 r.p.m. and when a circular reel is used, the reel speed is about 3040 r.p.m. These reel speeds have been found to be a significant factor in the preservation of the bulk during dyeing.

The term cellulose triester is used to define cellulose esters containing no more than 0.29, preferably 0 to 0.12 hydroxyl group per anhydroglucose unit in the molecule. The term cellulose triacetate further denotes cellulose acetates containing at least about 59%, preferably at least 61% of acetyl groups calculated as combined acetic acid by Weight.

The term cellulose triacetate yarn is used to denote yarns composed of 100% of cellulose triacetate and also yarns containing amounts, e.g., less than 50% by weight, of other fibers, in particular synthetic thermoplastic fibers such as nylon, polyester, acrylic and secondary cellulose acetate fibers and non-thermoplastic fibers such as rayon and natural fibers, e.g., cotton, linen and wool. Moreover, while the process is particularly suitable for the treatment of continuous multifilament yarns, it may also be applied to yarns spun from staple fibers.

The values of tensile strength, tenacity and initial modulus are based on ASTM Method D885-59T using an Instron Tensile Tester equipped with air operated jaws containing rubber facing and using a full load scale of 500 grams, a gage length of 10 inches, a cross head speed of 6 inches/minute and a chart speed of 5 inches/minute.

The crimp contraction is determined by preparing 5 skeins of the textured yarn, each containing 8 wraps having a diameter of one meter, wound with 0.01 gram tension. The skeins are treated in distilled water at 180 F for 10 minutes while relaxed, and are hung with a load of 0.1 gram/ denier for one minute while wet. The loop length of the skeins are then measured accurately, the total of the lengths of all the skeins at this point being designated as L After removal of the load, the skeins are dried at 150 F., cooled for one hour in a conditioned room at 23 C. and 60% relative humidity and while hanging in loop form without weights. A load of 0.001 gram/ denier is then applied to the skeins for one minute and the loop lengths of the skeins are again determined. The total of thelengths of all the skeins at this point is designated as L The crimp contraction, expressed in percent, is then equal to 100L 100 a I It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of our invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Process of texturing a cellulose triester yarn which comprises:

(a) feeding the yarn at a first feed rate through a temperature zone to a twisting zone;

(b) inserting a twist of from about 18 to 75 turns per inch into said yarn, said twist translating back along the yarn into the temperature zone;

(c) heating this said twisted yarn in said temperature zone to a temperature of about 170 to 200 C. for a period of about 4.5 to 0.03 seconds;

(d) substantially untwisting the twisted yarn while advancing it from said twisting zone at a second rate of speed of from about 99 to 109% that of said first rate; and

(e) taking up said yarn at a third rate of speed which is from about 100 to 70% that of said second rate of speed.

2. Process according to claim 1 wherein the yarn is continuous multifilament cellulose triacetate having a total denier of about 200, a twist of about 30 to 46 turns is inserted in the yarn, said twist being inserted in a direction opposite to that of any twist in the yarn forwarded to the twisting zone, the twisted yarn is heated to a temperature of from about 180 to 200 C. for a period of from about 3.0 to 0.03 seconds, the second rate of speed is from about 101 to 104% that of said first rate, and the yarn is taken up at a third rate of speed which is about 97 to 84% that of said second rate of speed.

3. The process of claim 2 wherein said yarn is a continuous multifilament yarn having a denier of about 200, a twist of about 32 to 36 turns per inch is inserted into the yarn, and the twisted yarn is heated to a temperature of about 185 to 195 C.

4. A textured continuous multifilament cellulose triacetate yarn produced according to claim 2, said yarn having a tenacity of about 1.1 to 1.3 grams/denier, an elongation of about 22 to 30%, an initial modulus of about to grams/ denier/ unit elongation and a crimp contraction of about 8 to 5. Process for obtaining a knitted fabric of cellulose triacetate of relatively high bulk comprising:

(a) texturing a cellulose triacetate yarn according to claim 1;

(b) knitting said yarn into a fabric under relatively uniform yarn tension;

(-0) tumble drying said knitted fabric at a temperature of at least 220 F. for a period of at least 20 minutes; and

(d) contacting the knitted and tumble dried fabric with steam at a temperature of about 250 to 280 F. for a period of about 20 to 40 minutes.

6. The process of claim 5 wherein said fabric is scoured and dyed to obtain a dyed fabric of high bulk.

7. The process of claim 5 wherein said yarn is a continuous multifilament yarn having a denier of about 200, a twist of about 32 to 36 turns per inch is inserted into the yarn, and the twisted yarn is heated to a temperature of about to C.

8. A process of texturing a cellulose triacetate yarn which comprises twisting said yarn such' that it contains about 30 to 46 turns per inch and subsequently untwisting the yarn, feeding the twisted yarn to a first temperature zone where it is heated while twisted to a temperature of about 180 to 200 C. for a period of about 3.0 to 0.03 seconds, feeding the yarn after it is substantially untwisted to a second temperature zone at a rate of about 101 to 104% that at which it is fed to said first temperature zone, advancing the yarn beyond said second temperature zone at -a rate of about 96 to 70% that at which it is fed to said second temperature zone and taking up the yarn at a rate of about 97.6 to 107.9% of the rate at which it is advanced beyond said second temperature zone.

9. Process for obtaining a knitted fabric of cellulose triacetate of relatively high bulk comprising:

(a) feeding a cellulose triacetate yarn at a first feed rate to a twisting zone;

(b) twisting said yarn such that it contains about 30 to 46 turns per inch;

(0) heating said twisted yarn in a first temperature zone to a temperature of about 180 to 200 C. for a period of about 3.0 to 0.03 seconds;

((1) substantially untwisting the twisted yarn while feeding it at a second feed rate to a second temperature zone, said second feed rate being about 101 to 104% that of said first feed rate;

(e) heating said untwisted yarn to a temperature of about 175 to 192 O;

(f) advancing the yarn beyond said temperature zone at a rate of about 96 to 70% that of said second feed rate;

(g) taking up the yarn at a rate of about 97.6 to

107.9% of said last-mentioned rate;

(h) knitting the yarn into a fabric;

(i) tumble drying the knitted fabric at a temperature of at least 220 F. for a period of at least 20 minutes;

and

(j) contacting the fabric with steam at a temperature of about 250 to 280 F. for a period of about 20 to 40 minutes.

10. The process of claim 9 wherein said fabric is scoured and dyed to obtain a dyed fabric of high bulk.

11. A textured cellulose triacetate yarn produced by the process of claim 1.

References Cited by the Examiner UNITED STATES PATENTS 2,869,318 1/1959 Stucki 57'157 3,029,591 4/1962 Scragg et a1. 57157 3,041,813 7/ 1962 Enneking 57157 X 3,077,724 2/ 1963 Stoddard et a1. 5734 FOREIGN PATENTS 1,140,992 3/ 1957 France. 1,217,137 12/1959 France.

850,693 10/ 1960 Great Britain. 908,514 10/1962 Great Britain.

FRANK J. COHEN, Primary Examiner.

I. PETRAKES, Assistant Examiner. 

9. PROCESS FOR OBTAINING A KNITTED FABRIC OF CELLULOSE TRIACETATE OF RELATIVELY HIGH BULK COMPRISING: (A) FEEDING A CELLULOSE TRIACETATE YARN AT A FIRST FEED RATE TO A TWISTING ZONE; (B) TWISTING SAID YARN SUCH THAT IT CONTAINS ABOUT 30 TO 46 TURNS PER INCH; (C) HEATING SAID TWISTED YARN IN A FIRST TEMPERATURE ZONE TO A TEMPERATURE OF ABOUT 180 TO 200*C. FOR A PERIOD OF ABOUT 3.0 TO 0.03 SECONDS; (D) SUBSTANTIALLY UNTWISTING THE TWISTED YARN WHILE FEEDING IT AT A SECOND FEED RATE TO A SECOND TEMPERATURE ZONE, SAID SECOND FEED RATE BEING ABOUT 101 TO 104% THAT OF SAID FIRST FEED RATE; (E) HEATING SAID UNTWISTED YARN TO A TEMPERATURE OF ABOUT 175 TO 192*C.; (F) ADVANCING THE YARN BEYOND SAID TEMPERATURE ZONE AT A RATE OF ABOUT 96 TO 70% THAT OF SAID SECOND FEED RATE; (G) TAKING UP THE YARN AT A RATE OF ABOUT 97.6 TO 107.9% OF SAID LAST-MENTIONED RATE; (H) KNITTING THE YARN INTO A FABRIC; (I) TUMBLE DRYING THE KNITTED FABRIC AT A TEMPERATURE OF AT LEAST 220*F. FOR A PERIOD OF AT LEAST 20 MINUTES; AND (J) CONTACTING THE FABRIC WITH STEAM AT A TEMPERATURE OF ABOUT 250 TO 280*F. FOR A PERIOD OF ABOUT 20 TO 40 MINUTES. 